Internal combustion engine systems are experiencing an increase in the use of turbochargers or superchargers. As is well known, a turbocharger includes a turbine wheel that is driven by the exhaust gases from the engine and which in turn drives a rotary compressor. A supercharger includes a rotary compressor which is directly driven by the engine or by a motor which is ultimately powered by the engine.
In either case, the rotary compressor compresses combustion air prior to its admission to the combustion chambers of the internal combustion engine. When a turbocharger is used, the system recovers part of the waste energy that results when incompletely spent exhaust gases are permitted to expand without performing work. Both types of system provide for higher compression ratios than are obtainable by the geometry of the internal combustion engine itself and allow the combustion of greater quantities of fuel for any given operating condition to provide an increase in engine power.
It has long been observed that when the incoming combustion air is compressed by the rotary compressor, it is simultaneously heated which, in turn, means that its density is decreased. Thus, at any given pressure, a unit volume of hot air from a turbocharger or a supercharger contains a lesser quantity of oxygen available for combustion than would an identical volume of cold air at the same pressure. This factor, in turn, places a limitation on the amount of fuel that may be burned in any given operating cycle of an internal combustion engine, which in turn limits the output thereof. Consequently, particularly in vehicular applications, a so-called charge air cooler has been introduced between compressor stages or between the compressor side of the turbocharger or supercharger and the intake manifold (or equivalent) for the internal combustion engine. The hot, combustion air from the turbocharger or the supercharger, is passed through the charge air cooler to the engine. At the same time, air or liquid is passed through the charge air cooler in a flow path isolated from the combustion air, but in heat exchange relation therewith. Cooling of the combustion air is obtained to increase the density of the combustion air to ultimately provide a greater quantity of oxygen per charge of air to the engine to support the combustion of a greater quantity of fuel, increasing the output of the engine.
The present invention is directed to improvements in liquid cooled charge air coolers.